Lamp socket and panel assembly with grounding switch

ABSTRACT

A lamp socket for detachable mounting on a panel includes an integral grounding switch which is closed by coaction with the panel to complete an electrical circuit to the lamp bulb only when the socket is in a properly mounted position.

United States Patent List et al. Jul 8 1975 LAMP SOCKET AND PANEL ASSEMBLY [56] References Cited WITH GROUNDING SWITCH UNITED S A P S [75] Inventors: Joseph 0. List, West Farmington; 2,849,697 8/1958 Farison 339/127 R Warren Pearce, Jr., Warren, both of 3,253,249 5/ 1966 Hess et al Ohio 3,559,152 1/1971 Pearce, Jr. 339/127 R 3,710,047 1/l973 Brzozowski et al ZOO/51.07 [73] Assignee: General Motors Corporation,

Detrolt Mlch' Primary ExaminerDavid Smith, Jr. 22 i 21 1974 Attorney, Agent, or FirmPeter D. Sachtjen [21] Appl. No.: 434,892 ABSTRACT A lamp socket for detachable mounting on a panel in- [52] 200/51'07; 42 5 cludes an integral grounding switch which is closed by Int Cl 50 coaction with the panel to complete an electrical cirn u u u u t t t l b l h k t [58] Field of Search zoo/51.07, 51.08, 51.09, cm o e amp u (my w en e Soc e m a ZOO/51.13, 51.1; 248/27; 339/127 R properly mounted position.

1 Claim, 9 Drawing Figures LAMP SOCKET AND PANEL ASSEMBLY WITH GROUNDING SWITCH The present inventiongrelates to' a lamp socket, an in particular, to a lamp socket and panel assemblyfor motor vehicles wherein the/lamp socket is provided with an integral grounding switch which is closed to complete an ,electrical circuit through a lamp bulb carried by the ,socket only when the socket is in a properly indexedposition on the panel. I l

Current lamp socket and panel assemblies fo motor vehicles comprise a socket which is detachably mounted on a nonconductive panel. The socket in-v cludes a. -metallic bulb holder carrying a lamp bulbl The holder is electrically connected to a grounding lead wire. The base contact of the bulb is conventionally connected to a lead wire connected to a circuit on the positive side of the battery. Accordingly,.when a bulb isin the holder, the bulb filament is energized regardless of the mountingposition.

While such an arrangement adequately provides the desired illuminationof the bulb filament in accordance with electrical circuit actuation, for certain applications such as automobile taillighting, the arrangement may not be entirely satisfactory. Therein, it is photometrically desirable that the bulb filament bear a predetermined, general horizontal, relationship with respect to the lamp lens. Otherwise, the optical'characteristics of the lighting unit are undesirably altered. Furthermore, it is desirable that a ready check be available to determine that the lamp sockets are in securely locked and indexed positions, Inasmuch as the aforementioned lamps, can be energized independentlyof the socket mounting orientation, an insecurely mounted light will erroneously give an illur'ni'nation appearance of being properly aligned. Subsequent vibration and use thus might dislodge the socketfrom its operative position. i a

Alamp socket assembly made in accordance with the present invention is detachably mountable on a panel member by means of cooperating lands and grooves on the panel in the socket. Only by inserting the forward end of the socket through an opening in the panel and then fully rotating the socket to an indexed position wherein the lands on the socket are engaging the lands of the panel is a grounding circuit completed for energizing the'bulb filament. The forward end of the socket includes a conductive bulb holder having prongs extending into a longitudinal cavity in thesocket. The prongs fixedly and electrically engage the cylindrical sidewall of a bayonet type lamp base on a negative or ground side of the filaments. The base of the bulb includes a conventional insulated contact which engages a terminal to complete an electrical conne'ctionto the positive or hot side of the filament. The bulb holder additionally includes three circumferentially spaced, reversely bent outwardly extending locking ears'which are inserted through mating grooves in the socket. When rotated, the ears compressively engage one side of the panel while an intermediate flange on the socket engages the other side of the panel. The bulb'holder further includes a contact which is normally spaced from the contact. leading to the socket grounding lead. In both embodiments disclosed herein, one of the contactsis a resilient cantilevered spring. This spring engages a camming surface on the'panel as the socket is rotated toward its indexedposition. This-biases the spring contact against the stationary contact to complete the grounding circuit with the lamp holder and through the bulb-filament only when thesocket is in the properly indexed position. By having the socket assembly connected to ground only when the lamp socket is properly secured to the panel, an, inspector at'final assembly for the motor vehicle can readilydetermine whether all of the lamp sockets have beenuproperly mounted, inasmuch as non-illumination would be indicative of the improper mounting. The above andother features of the present invention will be apparent to one skilled in the art upon read- FIG. 4 is a view similar. to FIG. ,3 showing the lamp socket with the spring contact at the cammingposition; FIG. 5 is a view similar to FIG. 3 showing the lamp socket at the indexed position wherein the sprin contact engages the groundingcontact; FIG. 6 is a view similar to FIG. 1 showing an alternate embodiment ofthe present invention with the lamp socket in spaced relationship to the panel;

FIG. 7 is a fragmentarycrosssectional view of the lamp socket with. the grounding contact and spring contact at the insertion position;

FIG-8 is a view similar to FIG. 7 showing the lamp socket with grounding'contact and the spring contact at the camming'position; and, I

FIG. 9' is a view similar to FIG. 7 showingvthe lamp socket with the grounding contact and the spring contact at the indexed closed position wherein the spring contact engages the grounding. contact.

Referring to the drawings, and in particular FIGS. '1.

, through 5, there'is shown a lamp socket and panel assembly wherein the lamp socket is readilyconnectable to and disconnectable from the panel, and when in position thereon, a light bulb carried by the socket is accurately indexed therewith to provide a lightingfunc lamp socket l2 holds a conventional bayonet type light bulb 14 as shown in dashed lines in FIG. 2.

The panel 10 may be the reflector for a taillight assembly and comprises at its rear central portion a thin wall reflector section 16 and a circular lamp mounting central section 18. The panel 10 forms a component of the lighting unit which is conventionally attached to the rear of the motor vehicle. The panel 10 is formed of a non-conductive plastic material such as vinyl. The front coating.

surface of the panel may be provided with reflective "Thecentral section 18 of the panel '10 includes a circular hub"20'having a central longitudinal opening 24 with an axis 2 "The opening 24 is peripherally bounded byairalternatingseries of inwardly projecting lands-26 and 'grooves 30. The-grooves 30 are substantially uniformly circumferentially spaced. For purposes hereaftei described, one of the grooves 30 is slightly larger than the others. I

Referringto FIG. 3,'a representative'land 26 is provided with an intermediate projecting indexing stop32 having an indexing ramp 33, an entry ramp 34, an an arcuateengagem'ent surface 36. A trailing portion 40 spaced onthe other side of the indexing stop 32 has a substantially arc-uate' planar-rear surface 42.

The. lam p socket- 12 comprises a body 44, a lamp holder 46, a grounding switch 48, a pair of input leads 50, and a g-rounding -lead'52.

The-body 44is a-o'ne piece molded member made froma' siiitable-elastomeric plastic material such as viny-lwThe body 44 broadly includes -a'frontal nose portion 54', a'rear-base portion 56, and an annular intermediate sealing flange 58. As shown in FIG. 2, the body 44 in'cludesafrontally opening cylindrical lamp cavity 60 communicating with the pair oflaterally spaced, axiallyextending terminal receptacles 62 opening rearwardly at the base portion 56. A pair of conventional spring terminals 64 are fixedly retained in the receptacles 62'and attached to the leads 50.

' The g'rouhding lead 52 is contained within a longitudinally axially extending terminal housing 66. The sealing' flange 58 is slightly larger in diameter than the opening 24 and terminates within annular forwardly projecting frontal lip 68. The lip 68 compressively sealingly engages the rear surface 42 of the hub 20 in assembly. To facilitate rotation of the body 44, the rear base portion 56 is provided with a'longitudinal tab 70. lnsconju'nction with" the housing 66, the tab 70 may be grasped to facilitate insertion and rotation of the socket The bulb holder 46 comprises a generally annular electrically conductive metallic stamping. The bulb holder 46 comprises an annular frontal ring section 71, three radially outwardly extending. circumferentially space'd locking and indexing ears 72, three reversely directed staking legs 74, and a pair of inner reversely directed contact terminals or prongs 76.

- Thestaking legs 74 are fixedly received within forwardly opening. slots 80in the-nose portion 54. The

lockingears'72'each include a reversely bent section terminatingwith rounded triangular tips 82. The hypotenuse of each tip 82 engages the ramp surfaces 33 on the stops 32'to interlock and index the socket 12 on the panel in final assembly. The tips 82 are axially spaced from the lip 68 slightly less than the thickness of the corresponding land 26. The cars 72 yield slightly to provide for compressive retention of the lands therebetween.

i The prongs 76, as shown in FIG. 2,.include a J- L shaped notch 84. The light bulb 14 comprises a spherical globe 88, a conductive cylindrical base 90, a pair of diametrically opposed locking lugs 92, and a pair of radially spaced contacts 94. The base and the contacts 94 are connected to the filament lead wires. Thus, the lamp bulb 14 is a-conventional bayonet type construction. The bulb '14 is axially inserted into the cavity 60 the filaments, however, it is necessary to close a grounding circuit established, as hereinafter described,

through the prongs 76, the grounding switch 48 and the grounding lead 52.

The grounding switch 48 comprises a stationary contact on the bulb holder 46 and spring contact 'par-' tially disposed within the housing 66.

The stationary contact has a generally L-shaped' grounding terminal projecting radially outwardly and rearwardly from a downwardly extending arm 102' adjacent one of the ears 72. The grounding terminal 100 is positioned, as shown in FIG. 3, substantially midway between a locating rib 104 on the nose portion 54 and the adjacent ear 72. The rib 104, the grounding terminal 100 and the ear 72 span an arcuate sector slightly less than that spanned by the large groove 30'. The spring contact further includes a fixed portion (not shown) housed within the housing 66 and a forwardly projecting cantilevered spring finger contact 106. The spring finger contact 106 is normally spaced from the grounding terminal 100 and closes thereagainst as the socket 12 is rotated into the indexed position. The spring finger contact 106 includes a camming lip 110 which cooperates with the leading surface of the land 36 to close the grounding circuit under the aforementioned conditions.

I More particularly, to mount the lamp socket 12 on the panel 10, the nose portion 54 is forwardly inserted through the opening 24 with the locking ears 72 registering with the associated groove 30 and the rib 104 and the adjacent locking ear 72 being positioned at the enlarged groove 30', (FIG. 3). The socket 12 is then forwardly inserted until the lip 68 engages the rear surface 42. The operator, by gripping the housing 66 and the tab 70, rotates the socket until the tips 82 of the cars 72 engage the ramps 34 at the camming position (FIG. 4). Upon further rotation the cars 72 slide up the ramps 34 onto the engagement surface 36, this being accommodated by limited yielding and flexing of the ear 72. Referring to FIG. 4, as the car 72 is rotated over the surface 36, the camming lip 110 of the spring contact 106 engages the forward corner of the ramp 34, a position which starts the inward camming action thereof. Referring to FIG. 5, further rotation of the socket .12 with respect to the panel 10 continues until the tip 82 of the ear 72 abuts the ramp 33 of the locating stop 32. In this position, the contact terminal 106 bears against the interior surface of the land 26 and is firmly closed against the terminal 100. Accordingly, this completes the electrical circuit to the bulb filament only when the socket is in the properly indexed position with respect to the panel. In the event the socket has not been rotated sufficiently to close the grounding circuit at the properly indexed condition, the circuit will not be closed, and .the failure to illuminate will be indicative of a mounting, problem- Moreover, should the socket inadvertently dislodge from its mounting position, the bulb 14 would be automatically distinguished, indicative of the dismounted condition.

In FIGS. 6 through 9, there is shown an alternate embodiment of the present invention incorporating a grounding circuit which is closed as the socket attains its fully indexed position on the panel. Therein, parts corresponding to the embodiment of FIGS. 1 through 5 are referenced by corresponding numbers carrying a prime designation.

More particularly the embodiment comprises a panel assembly 10 which detachably receives a socket 12. The panel includes a circular hub defining a central opening 24. The opening 24' is bounded by alternating grooves 30 and lands 32'. One of the grooves 31 is enlarged with respect to the others. Additionally, the hub 20 includes a radial notch 120 formed in the rear surface 122 thereof. The notch 120 includes a vertical wall 124 and an inclined ramp wall 126.

The body 44 of the socket 12 is substantially the same as the former embodiment and includes the ground terminal housing 66 and a rear base 56. The base 56' houses the leads 50 and 52'.

The bulb holder 46 is attached to the nose section 54 of the holder 46 and includes inner prongs 76 for gripping the cylindrical sidewall of the bulb. The holder 46 includes three radially outwardly disposed locking ears 72'.

In this embodiment the grounding switch 48 includes a stationary contact at the housing 66' and a spring contact at the holder. The grounding terminal on the housing 66 has an outwardly projecting fixed contact arm 100'. The spring finger 106' cooperates with the notch 120 to complete a grounding circuit as the socket 12' is rotated to its fully indexed position.

More particularly, in FIG. 7 the socket 12' is shown at its insertion position with respect to the panel 10'. Therein the ears 72 are aligned with associated grooves 30' and the flange 68 engages the rear surface of the hub 20'. In this position, the spring contact 106' is midway disposed in the notch 120 and is axially spaced from the stationary contact. The grounding circuit is thus open and the bulb filaments are extinguished. As the socket 12 is rotated with respect to the panel 10, the contact 106' traverses the notch 120 until the camming position is reached wherein the leading edge engages the ramp surface 126, (FIG. 8). As rotation of the socket 12' continues, tips of the locking ears 72' ride upwardly on the ramp surfaces of the lands and thereacross. The lands are compressively gripped between the ears 72' and the lip of the flange. Concurrently, the camming action between the ramp surface 126 and the contact 106' axially rearwardly biases the contact into electrical contact with the stationary contact, (FIG. 9). This completes the electrical circuit to the lamp bulb in a manner previously described. It insures a complete electrical circuit only when the socket has attained an indexed position with respect to the panel, the socket being restrained from movement by interengagement between the locking ears, the stop surfaces on the terminal parts of the land 32. Thus the lamp socket is not connected to ground until properly secured to the panel.

Although this invention has been shown and described with reference to the above embodiments, other forms will be readily apparent to those skilled in the art. Therefore, it is not intended to limit the scope of this invention by the embodiments selected for the purpose of this disclosure but only by the claims which follow.

What is claimed is:

1. A lamp socket and panel assembly comprising: a non-conductive panel, a central hub on said panel having an opening therein bounded by an outer peripheral surface defined by alternating lands and grooves; axially projecting stop surfaces on said hub adjacent said grooves; a radial notch in said hub having a camming surface thereon; a lamp socket formed of a nonconductive elastomeric material, said socket having a body with front and rear portions; an annular flange on said body intermediate said front and rear portions; a center longitudinal cavity in said front portion of the body adapted to receive the base of a lamp bulb having lead wires connected to the filaments thereof, said intermediate flange adapted to engage the peripheral surface of said panel; first and second terminal members carried by said socket adapted to be connected in an electrical circuit, one of said terminals being disposed in said cavity and adapted to engage one lead of said lamp bulb; an annular conductive bulb holder carried on the front portion; said holder having a plurality of integral flexible locking ears spaced circumferentially therearound adapted to register with said grooves at an insertion position, said ears having rounded triangular tips spaced from said flange by the thickness of said panel member and including a hypotenuse index surface thereon; a contact prong formed integrally on said holder extending into the cavity and adapted to electrically connect with the other lead of said lamp bulb, said holder having a radially extending cantilevered spring finger integrally formed thereon adapted to contact saidother terminal to complete an electrical circuit through the light bulb, said finger registering with said notch at said insertion position, said lamp socket being attachable to said panel by inserting said ears through said grooves and rotating the body with the locking ears passing across the surface of said lands until engagement of said hypotenuse index surface at an indexed position with said stop surface, said spring finger engaging Said camming surface at said notch as said socket is rotated to said indexed position to bias said spring finger against said other terminal to complete the electrical circuit through said bulb only when said socket is in an indexed condition on said panel member. 

1. A lamp socket and panel assembly comprising: a non-conductive panel, a central hub on said panel having an opening therein bounded by an outer peripheral surface defined by alternating lands and grooves; axially projecting stop surfaces on said hub adjacent said grooves; a radial notch in said hub having a camming surface thereon; a lamp socket formed of a nonconductive elastomeric material, said socket having a body with front and rear portions; an annular flange on said body intermediate said front and rear portions; a center longitudinal cavity in said front portion of the body adapted to receive the base of a lamp bulb having lead wires connected to the filaments thereof, said intermediate flange adapted to engage the peripheral surface of said panel; first and second terminal members carried by said socket adapted to be connected in an electrical circuit, one of said terminals being disposed in said cavity and adapted to engage one lead of said lamp bulb; an annular conductive bulb holder carried on the front portion; said holder having a plurality of integral flexible locking ears spaced circumferentially therearound adapted to register with said grooves at an insertion position, said ears having rounded triangular tips spaced from said flange by the thickness of said panel member and including a hypotenuse index surface thereon; a contact prong formed integrally on said holder extending into the cavity and adapted to electrically connect with the other lead of said lamp bulb, said holder having a radially extending cantilevEred spring finger integrally formed thereon adapted to contact said other terminal to complete an electrical circuit through the light bulb, said finger registering with said notch at said insertion position, said lamp socket being attachable to said panel by inserting said ears through said grooves and rotating the body with the locking ears passing across the surface of said lands until engagement of said hypotenuse index surface at an indexed position with said stop surface, said spring finger engaging said camming surface at said notch as said socket is rotated to said indexed position to bias said spring finger against said other terminal to complete the electrical circuit through said bulb only when said socket is in an indexed condition on said panel member. 